18F-labeled O-(2-[18F]fluoroethyl)-L-Tyrosine is an amino acid tracer, it has been proved as a suitable PET (position emission tomography) probe for tumor diagnosis imaging. Today, 2-[18F]Fluoro-2-Deoxy-D-glucose([18F]FDG) has been widely used as a PET agent for evaluate tumor diagnosis and treatment through biohemical pathway of glucose metabolism. Increase brain background radiation due to high absorption of [18F]FDG in the brain cause diagnosis difficulty of brain tumor; High [18F]FDG absorption of inflammation site also cause misjudgment. Brain tumor cells also have high concentration of L-[methyl-11C]methionine, but free of diagnosis difficulty and misjudgment as described above; nevertheless, the half-life of L-[methyl-11C]methionine is twenty minutes, therefore, attenuation rapidly during delivery with increasing cost even use cyclotron.
The absorption of 18F-labeled O-(2-[18F]fluoroethyl)-L-Tyrosine through biochemical pathway of amino acid metabolism almost the same as 11C-labeled L-[methyl-11C]methionine, the absorption by brain tumor is much lower than [18F]FDG and also by inflammation site. Half-life of both [18F]FET and [18F]FDG are 109 minutes, this will facilitate the delivery between hospitals, and commercialization is possible because of its cost is lower than 11C-labeled L-[methyl-11C]methionine.
The preparation of O-(2-[18F]fluoroethyl)-L-Tyrosine was developed by Wester et al. (J. Nucl. Med. 1999; 40:205–212) and Hamacher et al. (Appl. Radiat. Isot. 2002; 57:853–856). However, it is inconvenient by using high performance liquid chromatography (HPLC) for purified product, it is not only cumbersome but also difficult automation, since during HPLC purification process operator must switch valve from waste collecting bottle to product bottle in order to collect purified O-(2-[18F]fluoroethyl)-L-Tyrosine and switch valve back to waste bottle after complete the collection of purified product in order to maintain high purified O-(2-[18F]fluoroethyl)-L-Tyrosine. This procedure is impotent, since bad control of valve will cause loss or impurity product and manufacturer must face with problems of unqualified product and increasing cost of manufacturing equipment.